Road junctions



J. E. BURRELL July 30. 1968 ROAD JUNCT IONS 2 Sheets-Sheet 1 Filed March 28, 1966 y muqzll/i 'kw A Home y July 30. 1968 J. E. BURRELL. 3,394,638

ROAD JUNCTIONS Filed March 28, 1966 2 Sheets-Sheet 2 N r I no.2

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tlorne y United States Patent 3,394,638 ROAD JUNCTIONS John Edwin Bur-rel], 8 Chesham St., London SW. 1, England Filed Mar. 28, 1966, Ser. No. 537,815 Claims priority, application Great Britain, Mar. 29, 1965, 13,187/65 9 Claims. (Cl. 941) ABSTRACT OF THE DISCLOSURE A multi-level road junction comprises first and second trafiic arteries one of which crosses over the other so as to permit unobstructed passage of the vehicles along each artery. Each of the arteries includes two carriage-ways having each at least one traflic lane. Link roads interconnect the carriageways of one artery with the carriageways of the other artery.

This invention relates to an improved road junction or fly-over of the kind employed in motorway or main road systems in an area where two traffic arteries cross to permit unobstructed passage of vehicles along each artery and also to provide interconnecting link roads between the carriageways of one artery and the carriageways of the other artery.

Various suggestions have been made for the design of multi-level road junctions of the kind referred to and notable among these suggestions is the so-called cloverleaf junction.

For convenience in the ensuing description, the two intersecting trafiic arteries will be considered to be extending North-South and East-West and reference will accordingly be made to North-, South-, Eastand West-bound trafiic and Northwards, Southwards, Eastwards and Westwards, though it will be appreciated that these designations with reference to the compass points are employed for convenience of description and should not be interpreted as imposing any limitations on the geographical orientation of roads in practical road-junctions.

In a clover-leaf junction in a left-hand drive system, the interconnecting link roads for traffic wishing to make a left-hand change of direction (i.e. Northbound traffic wishing to continue Westwards, Eastbound traflic wishing to continue Northwards, Southbound traflic wishing to travel Eastwards or Westbound traffic wishing to travel Southwards) are formed by arcuate link roads (on which trafiic moves in an anti-clockwise direction) which turn through 90. The link roads for traffic wishing to execute a right-hand change of direction (i.e. Westbound traflic wishing to travel Northwards, Northbound traffic wishing to travel Eastwards, Eastbound trafiic wishing to travel Southwards and Southbound traflic wishing to travel Westwards) are formed by arcuate link roads (on which traffic again moves in an anti-clockwise direction) which turn through 270 and curve away from the actual crossing area. It is the necessity for providing the link roads for a 270 change of direction which utilises so much space at a clover-leaf crossing and which usually rules out the possibility of employing such junctions in densely built-up areas where space is very valuable. In the case of a clover-leaf junction in a right-hand drive system the transitions designated above as being 90 and 270 turns are reversed, but the problem of space utilised by a clover-leaf junction still arises.

This invention relates to an improved multi-level road junction between trafiic arteries which permits interchange from one artery to the other at the junction and yet provides a junction which requires much less space than that required for a comparable conventional clover-leaf junction.

The invention resides in the simple expedient of arranging for the carriageways of one of the arteries to be completely reversed compared with the carriageways of the other artery. In a right-hand drive system, such as is used in the majority of countries, each carriageway lies on the left-hand side of the driver of a vehicle proceeding along the other carriageway, whereas in a left-hand drive system, each carriageway lies onthe right-hand side of the driver of a vehicle proceeding along the other carriageway. The expression completely reversed carriageways used in this specification means, in the case of a righthand drive system, that all the lanes of each carriageway of that artery lie to the right of the driver of a vehicle proceeding along any lane of the other carriageway, and means, in the case of a left-hand drive system, that all the lanes of each carriageway of that artery lie to the left of the driver of a vehicle proceeding along any lane of the other carriageway.

By this simple expedient, it is possible to design a multi-level road junction in which the link roads are so arranged that traffic approaching the junction in any one of four possible directions can leave the junction in any of the other three directions but in which the link roads are retained close to the crossing area.

Thus, for example, if we consider a junction in accordance with the invention in a left-hand drive system in which a North-South artery passes above or below an East-West artery and has completely reversed carriageways compared with the East-West artery, then Northbound trafiic wishing to turn Eastwards, Southbound traffic wishing to turn Westwards, Eastbound trafiic wishing to turn Southwards and Westbound traffic wishing to turn Northwards each makes a turn to the right and Northbound traflic wishing to turn Westwards, Southbound traflic wishing to turn Eastwards, Westbound traffic wishing to turn Southwards and Eastbound trafiic wishing to turn Northwards each makes a 90 turn to the left.

By providing completely reversed carriageways on one artery in this Way, the need for any link road to curve through 270 is eliminated, so that a junction in accordance with the invention with all interconnecting link roads may be accommodated in an area little larger than would have been required for an over-pass without link roads.

Although the specification so far has concentrated on a junction in which the traffic arteries are disposed at 90 to each other, it will be appreciated that this is not an essential feature of a junction in accordance with the invention and that the space-saving advantages of a junction in which one artery has completely reversed carriageways are still obtained when the angle between the intersecting traflic arteries is not 90.

The invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which FIGURE 1 is a plan of a first embodiment of the road junction according to the invention,

FIGURES 2 to 4 are plans of parts of three modified embodiments of the junction of FIGURE 1,

FIGURE 5 is a plan of a carriageaway change-over section, and

FIGURE 6 is a diagrammatic plan of ring-road system comprising road junctions in accordance with the invention.

The road junction shown in FIGURE 1 is formed by a North-South traffic artery 1 passing over an East-West traflic artery 2. The artery 1 may be carried over the artery 2 by a bridge or the artery 2 may pass through a tunnel under the artery 1, the actual arrangement being of no importance so far as the invention is concerned.

The two arteries 1, 2 have central screens or barriers 3, 4, respectively, which divide the arteries into carriageways 5, 6 for the artery 1 and carriageways 7, 8 for the artery 2. At the intersection of the arteries, and a short distance each side thereof, the arteries 1, 2 are provided with barriers 9, 10 and 11, 12, respectively, disposed parallel to and spaced from the central barriers or screens 3, 4. The central barrier 3 and the two barriers 9, 10 define parallel carriageways 5a, 6a for through trafiic on the artery 1 and the central barrier 4 and the two barriers 11, 12 define parallel carriageways 7a, 8a for through traffic on the artery 2.

On the west side of the intersection two link roads 13, 14 lead from the artery 2 to the artery 1. These link roads branch from the outside lanes of the carriageways 7, 8 and are separated from the latter by barriers 15, 16. In like manner, two link roads 17, 18 on the east side of the intersection lead from the artery 2 to the artery 1, these roads being separated from the carriageways 7, 8 by barriers 19, 20. Other similarly arranged pairs of link roads 21, 22 and 23, 24 on the north and south sides, respectively, of the intersection lead from the artery 1 to the artery 2, barriers 25, 26, 27 and 28 being arranged to separate the link roads from the carriageways 5, 6. These link roads may have a width suitable for accommodating a single stream of traffic or a plurality of streams side by side, depending on the volume of traffic anticipated.

Between each link road and the adjacent barrier 9, 10, 11 or 12 there is formed a link lane, these eight link lanes being designated by the reference numerals 29 to 36. Each of these link lanes, which again may have a width suitable for accommodating a single stream of trafiic or a plurality of streams side by side, leads from a carriageway of an artery to the junction of a pair f link roads of the other artery.

Assuming that the area around the junction is approximately level, then, if the artery 1 is carried over the artery 2 by a bridge, the link roads 13, 14, 17 and 18 all incline upwardly from the artery 2 to artery 1. If, on the other hand, the artery 2 passes through a tunnel under the artery 1, then the link roads 21, 22, 23 and 24 incline downwardly from the artery 1 to the artery 2.

Assuming that the road junction is in a country where normally the traffic drives according to the right-hand drive system, it will be seen, from a consideration of the arrows which indicate the directions of traflic flow in FIGURE 1, that the carriageways 7, 8 of the artery 2 are completely reversed compared with the carriageways 5, 6 of the artery 1. From a consideration of FIGURE 1 it will be appreciated that traflic approaching the junction in either direction along either of the arteries 1, 2 can leave the junction in the same direction, can leave in either direction on the other artery or can execute a safe U-turn around the appropriate pair of link roads and return along the incoming artery in the opposite direction. This is achieved with link roads which only make 90 turns and in a junction having only two levels.

In order to eliminate any risk of the drivers of vehicles on the artery 2 being confused by the unfamiliar trafiic pattern, the central screen or barrier 4 ma be constructed so that drivers on either of the carriageways 7, 8 cannot see vehicles proceeding along the other carriageway of the artery 2.

At the junction of each pair of link roads there will be a certain amount of interference between traffic changing from one artery to the other. Thus in the region where the link roads 13, 14 join the link lanes 29 and 34 there will be interference between traflic leaving the carriageway 5 via link lane 29 wishing to pass on to carriageway 8 via link road 14 and traffic leaving carriageway 7 via link road 13 wishing to pass on to carriageway 5 via link lane 34. If the volume of traffic in one of the interfering directions is insignificant, the problem can be dealt with by making the trafiic in this direction come to a halt and give way to the crossing traffic. Alternatively, traffic signals may be used to control the interfering traffic flows. The link lanes and link roads may be made sufiiciently long to accommodate vehicles waiting for the trafiic signals to change.

If a considerable volume of traffic is likely to occur at one or more of the regions of interference, then one of the solutions indicated in FIGURES 2 and 3 may be adopted. In these figures the same reference numerals have been used as in FIGURE 1 to designate the same items in the three figures.

In FIGURE 2 the pair of link roads 13a and 14a do not join at the artery 1, but one passes over the other. This eliminates any interference between traffic leaving the carriageways 5 and 7 via the link lane 29 and the link road 13a, respectively. It has the drawbacks, however, that the junction becomes a three-level junction and that a U-turn is no longer possible from the carriageway 7 to the carriageway 8, unless a further link road (not shown) is provided for this purpose.

In FIGURE 3 the junction of the link roads 13b and 14b is elongated in the direction of the artery 1 to form a traffic weaving section 37. The section 37 is made sufficiently long so that vehicles entering it from the link road 13b and the link lane 29 can position themselves for departure via the link lane 34 and the link road 14b without seriously interfering with each other. In this junction the link roads 13b and 14b encompass a larger area than the link roads 13, 14 of FIGURE 1, but a far smaller area than the corresponding link roads of a conventional clover-leaf junction.

In the junctions described above it will be appreciated that the fastest traffic on the artery with the completely reversed carriageways will travel closest to the link roads and link lanes of that artery. This has the drawback that slow moving traffic wishing to leave or enter the artery has to cross the fastest moving traffic lane. In order to eliminate or alleviate this drawback one of the arrangements shown in FIGURE 4 may be adopted. On the west side of the junction in FIGURE 4, the link roads 13c :and 14c commence at the centre of artery 2 and rise relative to the carriageways 7 and 8 before turning out to the edge of the latter so that through traffic can pass under them. The link lanes 35c and 360 in this case branch off the link roads and descend from the link roads to the artery 1. This arrangement completely eliminates the need for slow moving traflic leaving and entering artery 2 having to cross the fastest trafific lanes on the artery. On the east side of the junction in FIGURE 4, the link roads 17c and 18c commence at the centre of artery 2 and remain close thereto. The link lanes 31c and 320 are at the outer edges of the carriageways 7 and 8. In this arrangement slow moving traffic wishing to leave or enter the artery 2 via the link roads 17c and does not have to cross the fastest traffic lanes on the artery. The link roads 17c and 180 may join one another at the artery 1 in the manner shown, or they may be so shaped in the region where they joint that trafiic may make a U-turn from the link road 180 to the link road 17c. Alternatively, one of the link roads 17c and 180 may cross the other, as in the case of the link roads 13a, 14a of FIGURE 2. In this case, however, the crossing of one link road by the other can be effected while retaining a two-level junction. Again, the link roads 17c and 180 may be joined by a trafiic weaving section.

If necessary, a road junction in accordance with the invention may comprise two, or all three, of the features of FIGURES 2 to 4. Thus, for example, in the road junction shown in FIGURE 4, the juntcion of the link roads 21 and 22 may be elongated by a trafiic weaving section of the kind shOWn in FIGURE 3 and the link roads 23 and 24 may cross at different levels like the link roads 13a and 14a of FIGURE 2.

The artery with completely reversed carriageways (i.e. the artery 1 in a left-hand drive system or the artery 2 in a right-hand drive system) may be associated with carriageway change-over sections (permitting the carriageways to revert to the conventional arrangement) adjacent to the junction. Such a change-over section, which is located at a distance from the junction, permits the traffic to change over from left to right, and vice versa. As shown in FIGURE 5 it includes a section 38 comprising a bridge or underpass enabling the carriageway 8 to cross over the carriageway 7. It will, of course, be appreciated that, if desired, the carriageway 7 may cross over the carriageway 8 as an alternative to the arrangement illustrated.

In an area where a series of successive intersections occurs, however, it is convenient to have completely reversed carriageways over a length of artery sufficiently long to encompass the series of intersections and to provide change-over sections only at each end of the length of artery.

Thus a trafiic system for an entire urban area could be built up using space-saving junctions in accordance with the invention in which North-South arteries employed conventional carriageways and East-West arteries employed completely reversed carriageways, each artery with reversed carriageways having carriageway changeover sections only on the outskirts of the urban area.

In the case where a ring road intersects a series of other roads, the entire ring road may be made with completely reversed carriageways. Such an arrangement is shown diagrammatically in FIGURE 6, in which a ring road 39 intersects a plurality of roads 40a, 40b, 40c. Junctions in accordance with the invention are provided at each of the regions 41-44 indicated in chain lines in the figure. The carriageways 45, 46 of the ring road are completely reversed, whereas the normal arrangement of carriageways is provided on the roads 40a40c. With this arrangement no carriageway change-over sections for the carriageways of the ring road are required.

Although the specific embodiments of road junctions illustrated in the drawings employ eight link roads so that all possibilities of interchange at a junction are provided for, it will be appreciated that if desired, a junction could be constructed with some link roads omitted. Again, it is not essential for the junction to provide the possibility of executing U-turns at the junction.

In the above description it has been assumed that on the artery with completely reversed carriageways traflic will continue to adhere to the same rule of the road to which it is accustomed. There is, of course, nothing to prevent traffic being made to adopt the opposite rule of the road on the artery with completely reversed carriageways. While this may not be advisable in the case of a single junction, it leads to a particularly favourable solution in the case where the artery with completely reversed carriageways is an endless ring road. Thus junctions of the kind illustrated in FIGURES 1 to 3 may be employed and the slower moving traffic lanes will be adjacent to the link roads and link lanes on both arteries.

I claim:

1. A multi-level road junction, comprising a first traffic artery and a second traflic artery each having an approach carriageway and a departure carriageway for through traffic travelling in opposite directions with the carriageways of one artery crossing the carriageways of the other artery at different levels, the carriageways of one of said arteries carrying traffic according to a righthand drive system and the carriageways of the other of said arteries carrying trafiic according to a left-hand drive system; first left-turn link roads branching from the approach carriageways of said first artery and crossing at least part of the first artery at a different level from the first artery and connecting with the departure carriageways of said second artery; first right-turn link roads branching from the approach carriageways of said first artery and crossing at least part of said second artery at a different level from the second artery and connecting with the departure carriageways of the second artery; second left-turn link roads branching from the approach carriageways of said second artery and crossing at least part of said first artery at a different level from the first artery and connecting with the departure carriageways of the first artery; and second right-turn link roads branching from the approach carriageways of said second artery and crossing at least part of the second artery at a different level from the second artery and connecting with the departure carriageways of said first artery, each of said left and right-turn link roads changing the direction of trafiic which travels thereon from one to the other of said arteries between one and the other of said drive systems.

2. A multi-level road junction as defined in claim 1, wherein at least one of said first left-turn link roads has a portion in common with one of said second leftturn link roads, and at least one of said first right-turn link roads has a portion in common with one of said second right-turn link roads.

3. A multi-level road junction as defined in claim 1, wherein the departure and approach carriageways of one of said arteries cross each other on different level-s at points remote from and on opposite sides of the other artery.

4. In a road system, a plurality of road junction-s as defined in claim 1, one of said arteries being common to all of said junctions.

5. In a road system as defined in claim 4, wherein the departure and approach carriageways of said one artery which is common to all of said junctions cross each other at different levels at the beginning and at the end of the road system.

6. In a road system, a plurality of road junctions as defined in claim 1, one of said arteries being common to all of said junctions and said one artery being in form of an endless ring road.

7. A multi-level road junction as defined in claim 1, wherein at least some of the link roads join at least one of the arteries adjacent to the outer sides of the carriageways.

8. A multi-level road junction as defined in claim 1, wherein at least some of the link roads join at least one of the arteries at the inner sides of the carriageways.

9. A multi-level road junction, comprising a first trafiic artery and a second traffic artery each having an approach carriageway and a departure carriageway for through traffic travelling in opposite directions with the carriageways of one artery crossing the carriageways of the other artery at different levels, the carriageways of one of said arteries carrying trafiic according to a righthand drive system and the carriageways of the other of said arteries carrying trafiic according to a left-hand drive system; first left-turn link road branching from an approach carriageway of said first artery and crossing at least part of the first artery at a different level from the first artery and connecting with the departure carriage- Way of said second artery lying to the left of the first artery; a first right-turn link road branching from an approach carriageway of said first artery and crossing at least part of said second artery at a different level from the second artery and connecting with the departure carriageway of the second artery lying to the right of the first artery; a second left-turn link road branching from an approach carriageway of said second artery and crossing at least part of said first artery at a different level from the first artery and connecting with the departure carriageway of the first artery lying to the left of the second artery; and a second right-turn link road branching from an approach carriageway of said second artery and 7 8 crossing at least part of the second artery at a different References Cited level from the second artery and connecting with the departure carriageway of said first artery lying to the right UNITED STATES PATENTS of said second artery, each of said left and right-turn link 2,949,067 8/1960 Cedeno 941 roads changing the direction of trafiic which travels 5 3,238,854 3/1966 Okubo 941 thereon from one to the other of said arteries between one and the other of said drive systems. JACOB L. NACKENOFF, Primary Examiner. 

